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mikegett · 07-18-2006, 08:59 PM

Unfortunately, it won't be as simple as getting a 12 volt signal to lower the gain. The PPL gain control signal does not come from the HU. It comes from the CAN network into the HU and then out to the F8 amplifier input. I can't read the small print, but the first page shows it as a purple line. Possibly B6? Most likely, this is a RS232 serial connection. The bad news is that RS232's communicate both ways. Remove one, and they both stop functioning. This is why you loose the amp turn on when the HU is removed. The CAN stops sending the signal to the amp. The good news is that it may still be possible to mimick the signal. If you can locate the PPL line comming into the HU (I think it is B6), you can test it out. Just remove the PPL line coming into the HU and connect it to the PPL line (F8 on the amp). You are looking to see if the CAN will send the signal even though the OEM HU is removed. If the hiss went away, then your good. If not, then you may still have a option. I believe the PPL line is being recieved by the HU. The HU then outputs the desired range deepending on the driving conditions. If the HU wasn't altering the signal, then the CAN would simply send it straight to the amp like the amp turn on. Unless, the amp turn on may be seperate from the HU due to trim level options. In this case, the PPL signal may simply pass through the HU and all gain variations are performed at the CAN. If the later is true, then a Peripheral module may allow the CAN to send the signal to the amp with a aftermarket HU. I would first try connecting the two signals with your afermarket HU. You may get lucky. If it doesn't work, then plug your OEM HU back in, with the two PPL signals routed around the OEM HU. If the amp gain functions correctly, then the Peripheral module should work great. The Peripheral would also allow you to have retained power and all warning lights again. The downside is that the module costs about 100 dollars on sounddomain. Good luck, and keep me informed. You've actualy made me miss the alero. Mike Gettinger.

07-18-2006, 08:59 PM	#7
mikegett GL Member Join Date: Mar 2004 Location: connersville, Indiana (don't ask, it's not worth it) Posts: 980	Unfortunately, it won't be as simple as getting a 12 volt signal to lower the gain. The PPL gain control signal does not come from the HU. It comes from the CAN network into the HU and then out to the F8 amplifier input. I can't read the small print, but the first page shows it as a purple line. Possibly B6? Most likely, this is a RS232 serial connection. The bad news is that RS232's communicate both ways. Remove one, and they both stop functioning. This is why you loose the amp turn on when the HU is removed. The CAN stops sending the signal to the amp. The good news is that it may still be possible to mimick the signal. If you can locate the PPL line comming into the HU (I think it is B6), you can test it out. Just remove the PPL line coming into the HU and connect it to the PPL line (F8 on the amp). You are looking to see if the CAN will send the signal even though the OEM HU is removed. If the hiss went away, then your good. If not, then you may still have a option. I believe the PPL line is being recieved by the HU. The HU then outputs the desired range deepending on the driving conditions. If the HU wasn't altering the signal, then the CAN would simply send it straight to the amp like the amp turn on. Unless, the amp turn on may be seperate from the HU due to trim level options. In this case, the PPL signal may simply pass through the HU and all gain variations are performed at the CAN. If the later is true, then a Peripheral module may allow the CAN to send the signal to the amp with a aftermarket HU. I would first try connecting the two signals with your afermarket HU. You may get lucky. If it doesn't work, then plug your OEM HU back in, with the two PPL signals routed around the OEM HU. If the amp gain functions correctly, then the Peripheral module should work great. The Peripheral would also allow you to have retained power and all warning lights again. The downside is that the module costs about 100 dollars on sounddomain. Good luck, and keep me informed. You've actualy made me miss the alero. Mike Gettinger. __________________ 2003 Maroon Alero GLS Sedan. (Purchased new in 2003 with 18 miles, and sold in 2006) 2004 Toyota Corolla LE (Purchased new in 2003 with 87 original miles) 2007 Toyota Camry LE (12 original miles)